Conventionally, resistance variation memory cell that use a material of which resistance value changes in accordance with an application of a voltage is proposed. Such a resistance variation has two types of operation modes (unipolar and bipolar). The unipolar operation mode causes the memory cell to transition between a high resistance state and a low resistance state by controlling a voltage value and a voltage application time without switching a polarity of the applied voltage. The bipolar operation mode causes the memory cells to transition between the high resistance state and the low resistance state by switching the polarity of the applied voltage.
Due to the bipolar operation mode having a superior directional control compared to the unipolar operation mode, a number of pulse application necessary for causing the transition to the respective states is smaller in the bipolar operation mode than in the unipolar operation mode. Thus, the bipolar operation mode is capable of faster operation than the unipolar operation mode. In the bipolar operation mode, a set pulse is applied upon setting the memory cells in the low resistance state (set state). However, there exist memory cells that do not transition to the set state despite the set pulse being applied. Most of such memory cells do not transition in a setting direction, but rather comes to be in the high resistance state that is at or less than a resetting level.